The present invention relates generally to devices, systems and methods for material fixation. More particularly, the invention relates to a new and novel tendon-to-bone fixation system.
One of the most common needs in orthopedic surgery is the fixation of tendon to bone. The fixation of diseased tendons into a modified position is called tenodesis and is commonly required in patients with injury to the long head of the biceps tendon in the shoulder. In addition, tendons which are torn from their insertion site into bone also frequently require repair. This includes distal biceps tendon tears, rotator cuff tears, and torn flexor tendons in the hand. Tendons are also frequently used in the reconstruction of unstable joints. Common examples include anterior cruciate ligament and collateral ligament reconstructions of the knee, medial and lateral elbow collateral ligament reconstructions, ankle collateral ligament reconstruction, finger and hand collateral ligament reconstructions and the like. The commonly assigned U.S. Pat. Nos. 7,879,094 and 8,206,446, already incorporated by reference herein, describe devices and techniques for performing these types of procedures, utilizing, for example, the AperFix® femoral implant.
Currently, two different sources are utilized for the tissue that replaces the injured native Anterior Cruciate Ligament (ACL). When the new tissue comes from the patient's own body, the new graft is referred to as an “autograft”, and when cadaveric tissue is used, the new graft is referred to as an “allograft”. The most common autograft ACL reconstruction performed currently is the bone-patellar tendon-bone (BTB) graft. The BTB graft fixed with an interference screw is used more often because it more accurately replicates the native ACL due to its aperture compression at the femoral tunnel aperture. However, BTB reconstructions result in an increased rate of anterior knee pain post-surgically for periods of up to three years after reconstruction. Additionally, the harvest procedure for the BTB autograft is invasive, and can be difficult to perform. Alternatively, the hamstring tendon autograft ACL reconstruction technique does not result in any significant post-surgical pain, and the harvest procedure is minimally invasive compared to the BTB graft harvest. The reason that the hamstring tendon autograft procedure is not used more frequently in ACL reconstructions is that the fixation of the hamstring tendons to the femur and tibia are not as strong as the fixation of the BTB autografts.
Many systems have addressed some of the problems associated with ACL reconstruction using hamstring tendons, but there is not one system that addresses them all. The EndoButton by Smith & Nephew is easy to use and does not need additional drill holes. However, it does require additional accessories and additional people to perform the procedure, and does not replicate the native ACL due to a lack of tendon-to-bone compression at the aperture as well as additional length of tendon between fixation points. The EndoButton is an example of a cortical-only hamstring fixation device that yields a longer graft construct, resulting in a graft that is less stiff than the native ACL. Peer-reviewed journal data show that existing soft tissue fixation systems with long graft lengths between fixation points have as much as a 56% reduction in graft stiffness when compared to the native ACL.
The Arthrex TightRope DB is also a cortical fixation device that also incorporates a wedge that is pulled between the tendon bundles. This separates the bundles, but the wedge doesn't expand.
The Rigid Fix by Mitek is a cross-pin device that requires multiple drill holes, additional instruments, and assistance from other people in the operating room to complete the repair. Also, there is only passive compression of tendon-to-bone, not direct, active compression.
The Stratis ST by Scandius attempts to more accurately replicate the native ACL by adding material to take up space in the femoral tunnel, resulting in more intimate contact between the tendon and the bone. However, to insert the device into the femoral tunnel, the cross-sectional area must be less than the cross-sectional area of the hole. Therefore, there is no real compression of tendon to bone. The Stratis ST also requires additional drill holes, accessories, and people to perform the procedure.
EZLoc, by Arthrotek gives high strength and attempts to more accurately replicate the native ACL in the same fashion as the Stratis ST by taking up the space in the tunnel. This does create more intimate contact between the tendon and bone, but does not offer real compression at the aperture.
The Mitek Femoral IntraFix is an interference screw device that incorporates a sheath to protect the graft during screw insertion. Since it is a compression device, there is no active engagement of the implant with the tunnel wall.
Interference screws such as the RCI screw by Smith & Nephew and RetroScrew by Arthrex are easy to use and provide compression of tendon to bone at the femoral tunnel aperture. However, the pull-out strength and stiffness of the repair are significantly lower than in the preceding systems.